1. Field of the Invention
The present invention relates to an optical module and an input apparatus using the same and, more particularly, to an optical module movable on a display in response to a user's instruction and an input apparatus using the same.
2. Description of Related Art
In general, an input apparatus using an optical module is widely being used in various applications, e.g., handheld terminals such as a cellular phone and a personal digital assistant (PDA), a remote controller, an optical mouse for a computer, and so on.
The optical mouse among the above input apparatuses is a peripheral device of the computer for indicating a desired position using a cursor displayed on a screen. Here, the optical mouse includes an optical module for detecting a moved position of the optical mouse using reflection of light radiated from a light source.
Hereinafter, a process of detecting a moved state of an optical mouse using an optical module will be described with reference to FIG. 1.
The optical mouse using an optical module detects movement of an x-axis and/or a y-axis using reflection of light radiated from a light source 12, for example, a light emitting diode. That is, the light radiated from the light source 12 is reflected by a subject 15, for example, a flat surface at which the optical mouse is positioned. Then, the light reflected from the subject 15 is collected through a lens 20 installed in the optical mouse and is received into a sensor 14.
As described above, the sensor 14 receiving the light radiated from the light source 12 and reflected from the subject 15 detects x and y-axis movement of the optical mouse using variation of the light received therein, and outputs a predetermined signal corresponding to the movement to transmit the signal to a micro control unit (MCU) 40. Then, the signal output as described above is transmitted to a computer 50 together with data input by a button 45.
In addition, as shown in FIG. 2, the conventional optical mouse for detecting movement of the optical mouse through the above processes includes a base plate 30, and an optical module disposed on the base plate 30 to detect movement of the optical mouse. In this process, the optical module includes a lens 20 installed at an upper surface of the base plate 30, and a circuit board 10 disposed on the lens 20 and having a sensor 14 and a light source 12 installed therein. Here, a sensor 14 and a MCU can be integrated into a single die.
Meanwhile, in the process of assembling the conventional optical mouse, the optical module, i.e., the circuit board 10 having the sensor 14 and the light source 12 installed therein and the lens 20 are separately assembled to each other, and then the optical module is separately assembled to the base plate 30. As described above, when the separately assembled optical module and base plate 30 are assembled to each other, tolerance may occur.
For example, although the base plate 30 is formed using the same mold to have a thickness of 2.4±0.2 mm, the formed base plate 30 may be finely deformed due to heat treatment, material characteristics and so on. Then, when the lens is disposed on an upper surface of the deformed base plate and the circuit board is disposed on the lens, it is difficult to obtain flatness or uniform height required by the sensor installed in the circuit board.
Therefore, it is difficult for the separately fabricated optical mouse to have a certain depth of focus (DOF) due to the tolerance occurred when the circuit board, the lens and the base plate are assembled to each other. In this process, the above problems may be similarly applied to all kinds of input apparatuses using the optical module, e.g., handheld terminals, remote controllers, and so on.
As a result, it is impossible for the sensor of the conventional optical mouse to have a certain depth of focus since it is difficult to maintain mechanical dimensions uniformly, so that each mouse cannot precisely detect movement of the optical mouse.